Circuit interrupter



May 22, 1928. Y 1,671,023

J. T. l-'lTzslMMoNsr C IRCUIT INTERRUPTER Filed Jan.16, 1926 PatentedMay 22, 1928.

UNITED I STATES PATENT OFFICE.

JOHN T. FITZSIMMONS, OF DAYTON, OHIO, ASSIGNOR, yBY MESNE ASSIGNMENTS,TO DELCO-BEMY CORPORATION, OF DAYTON, OHIO, A CORPORATION OF DELAWARE.

CIRCUIT INTEBBUPTER.

I applic-atm mea January 16, 1926. serial No. 81,756.

ly to increase the' resistance thereof, at,

which time the extra heavy drain on the current source is materiallyreduced. Thisv drain becomes material in the lighting system for motorbusses which are generally provided with a large number of lamps, allused at the same time.

One of the primary objects of the present invention is tov provide aprotective or limiting device in circuit with the lamps of theilluminating system or other work devices of a motor vehicle, which,when an abnormal ow or surge of current passes therethrough due to thecold condition of the lamp laments "or to a short-circuit of any of theWork devices, will open the main circuit between the current source andsuch lamps or work devices and establish a higher-resistance, secondarycircuit to such lamps or work devices. This secondary high-resistancecircuit is maintained until the resistance of the lamps is built up to aproper value by the warming of the filaments, or until the short-circuiton any of the work devices is removed, at which time the maincircuitwill a ain be restored.

Further objects an advantages of the present invention will be apparentfrom the ollowing description, reference being hadto the accompanyingdrawings, wherein a preferred form of the present invention is clearlyshown.

In the drawings:

Fig. 1 is a diagrammatic, fragmentary view showing the circuitinterrupter and its electrical connections with theysource of currentand work devices.

Fig. 2 is a detail sectional view showing the core construction and itsplunger armaure.

Referring to the drawings, the numeral 2O designates a base of eitherinsulation or non-magnetic material upon which is mounted the circuitinterrupter.

The interrupter comprises a field frame 21, of U-shaped construction,having le 22 and 23, and cross-arm 24. The leg 22 has a foot 25 arrangedat right angle thereto, said foot having an aperture in which aninsulating collar 26 is provided. The foot is secured to the base 20 bymeans of stud 27, insulating washers 28 and 29 being placed between thefoot and base, and foot and stud nut 30, respectively.

By referring' to Fig. 2, the core of the electromagnetis showncomprising a main body portion 31, one end of which is reduced as at 32.This reduced portion 32 extends into an. aperture in the cross-arm 24 ofthe field frame 21, the edge of said portion 32 extending beyond theouter surface of said cross-arm and is spun or riveted over so that thecore is secured rigidly to the field frame.

The aperture in the cross-arm 24 is so positioned that the core liesmidway between the two arms 22 and 23. An insulating collar 33 isprovided between the cross-arm 24 and the core.

The core has a central, longitudinal passage 34 throughout its entirelength, this passage, however,.being of larger diameter in the main bodyportion 31 than in the reduced portion 32. This variation'in thediameter of the passage forms the shoulder 35. A sleeve 36, of anysuitable non-mag netic material, ts snugly around the core portion 31,one end lof said sleeve 36 abutting against the insulating collar 33,while the otherend has a flange 37. An insulating collar 38 fits aboutthe sleeve 36 and rests on the fiangey 37.

The lplunger armature is designated by of the frame and said head. A reuced portion 41 of such a diameter 4that only a small gap is formedbetween the legs 22 and 23 of the frame and said head. A reduced portion42 extends into the larger diameter por-v tion ofthe passage 34 in thecore so that a sliding fit obtains. A stem 43, extending from theportion 42 and of lesser diameter,

projects through the smaller diameter por- -said spring tending to push'the armature into engagement with the base 20, as shown in Fig. l1.

On the lcv 23 there is secured a spring arm whic 1 has a portion 46 bentover to lie parallel with the cross-arm 24. On this cross-arm there isprovided an insulating block 47 to which is secured a hollow contactmember 48 so arrangedfon said field frame 21 that the stem 43 of thearmature may pass through said hollow contact member 48 and engage themovable contact meniber 49, carried by the spring arm portion 46, insuch a manner that it will normally lie in engagement with saidstationary Contact.

An extension 50 to the portion 46 carries the movable member 51 of theauxiliary contacts, the stationary member 52 thereof being secured "tothe interrupter and insulated therefrom in any suitable manner. Theseauxiliary contacts 51 and 52 are always open when the main contacts 48and 49 are closed,

rushof current is substantially reduced. u

Supposing, for example, all the lights57 are simultaneously introducedinto the circuit by the closing of switches 58. initial rushof asubstantially heavy current How will leave the battery, flow through ThelBy the use of this interrupter, this initial winding 53 across contacts48 and 49,

gage the contact member 49 and move it out of engagement with itscooperating contact l 48, thus breaking the circuit through winding 53.Now, the iiow of current from the battery will deviate and pass' throughthe higher resistance winding 54 on its way to the lights, thussubstantially reducing the How from the battery while still maintainingthe armature in attracted position due to the direction of How throughthe winding 54.

Opening of contacts 48 and'49 will close and are always closed when thelatter vare ;the auxiliary .contacts 51 and 52. However,

opened by the armature.

Three windings 53, 54 and 55 are carried by the core. Winding 53 is oflow resistance and has its one end connected to the main stationarycontact 48, while its other end is in circuit connection with the sourceof current, shown to 4be abattery 56. Winding 54 is wound in the samedirection as 53, but is of greater resistance 'than said Winding 53. Oneof its ends is grounded on the le 22, or any other suitable portion ofthe fiel frame 21, while its other end is connected to the source ofcurrent 56. Thus, the wind-. ing 54 is connecte-d in parallel withwinding 53 and in shunt with the contacts48 and 49. The winding 55 is,wound reversely to the windings 53 and 54, and is of,k lesser resistancethan the winding 54 but greater than the `winding'53. Its one end isconnected to the auxiliary stationary contact member 52, while theopposite end thereofl is grounded to. connect with the ground of thebattery 56.

Work devices shown as lights 57 are adapted to be connected to theinterrupter foot 25 by means of switches 58. .On ymotor vehicles, lightshaving tungsten filaments are most commonly used.' It is well-known thattungsten, when cold, offers very little resist ance to -current How, soythat when a `tungsten filament light is first connected in circuit, agreat rush of current will at first occur, this current flow beingreduced as the filament in the light warms up. Where a great y number ofsuch lights are turned on, quite a bit of electrical energy -isuselessly expended l before the filaments are warmed sufficiently to oera normal resistance to the current flow. a Y

i as the resistance of the Work circuit is much less than the resistanceof Winding 55, which is now connected in series with winding 54, thecurrent will continue to flowthrough the work circuit until thefilaments of the lights have become sufficiently warm to offersubstantially the same resistance as winding 55. When this occurs, partof they current will `dev`iate and flow from the winding 54,l

through frame 21, spring arm 45 and its portions 46 and 50 acrosscontacts 5l and 52 through winding 55 back, to the battery via theground connections. l Winding 55 being reversed to Winding 54, it willdestroy the effect of winding 54 and permit -the spring 44 to return thearmature to its normal,"inoperativc position on the base 20. This closescontacts 48 and 49 andrestores' 'the circuit through the low-resistancewin'd-v mits an excessive fiowof current through the ,Winding 53, thiswinding -fwill energize the core 31 sothat the armature 40 will be movedto opent-contacts 48and 49 as described. The,

winding 54 being connected in' parallel with winding 53, will maintainthe armature in -the. contact-opening position as long as the TheI'short-circuit is permitted to exist.

shortlcircuit being of lesser resistance than the reverse winding 55, asubstantial current flow through said Winding will thus be preeludedand, therefore, no opposing effect will obtain against the holdingeffect of the windlng 54. rHowever,\as soon as the short-circuit isremoved,the resistance of the circuit will be restored to normal,causing a deviation of part of the current iow from said circuit,through the circuit including the i'everse winding, thereby bringinginto operation the demagnetizing effect' of said winding and thusrestoring the low-resistance circuit through winding 53 by the return ofthe armature and consequent closing of contacts 48 and 49.

While the form of embodiment of the invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is `as-ollows:

1. A protective device for circuits including work devices, comprisingin combination, a solenoid magnet provided with a pair. ofnormally-closed Icontacts and a hollow core containing a plungerarmature, said core having a plurality ,of windings wound about it, oneof said windings being adapted to open the contacts when the resistanceof the work circuit is reduced below alininimum allowable value, anotherwinding being adapted to hold said contacts open while such lowresista-nce is maintained in the work circuit, the third winding beingprovided for counteracting said holding winding and pei'- mitting thecontacts to close when theJresistance in the work circuit is againrestored tol its minimum allowable value.

2. A protective device for circuits including work devices, comprisingin combination, a solenoid magnet provided with a pairv ofnormally-closed contacts and a hollow core including a plunger armature,said core having a plurality 'of windings wound about it, one of whichis adapted to open the contacts when the resista-nce of the work circuitis reduced below a minimum allowable value, another being adapted tohold said contacts open while such low resistance is maintained in thework circuit, the third winding being adapted to be brought into circuitby the opening of the vcontacts for counteracting said holding windingand'permitting the contacts to close when the resistance in the workcircuit is again restored to its minimum allowable value.

8. A protective device for circuits including work devices, comprisingin combination, a solenoid magnet having a pair of normally-closed maincontacts; a pair of normally-open, auxiliary contacts andl threewindings about a common core, one winding being adapted to open the maincontacts' and to close the auxiliary'contactswhen lthe resistanceof thework circuit is reduced below a minimum allowable value, the secondwinding being provided for holding the main contacts openJ and theauxiliary contacts closed j-while the resist-ance in the work circuit ismaintained at'a value below the mum allowable value; and the thirdwinding in circuit with the auxiliary contact for counteracting saidholding means and permitting the main contacts to be closed when theresistance, in the work circuit is again restored to its minimum'allowable value.

4. A protective device for circuits including work devices, comprisingin combination, a solenoid magnet having a hollow core surrounded by amain electromagnet winding, aI secondary electiomagnet winding and acounteracting winding, said coi'e having a plunger armature therein andsupporting a pair of normally-closed contacts; the main electromagnetwinding being adapted to open the contacts when the resistance in thework circuit is reduced below a minimum allowable value, the secondaryelectromagnetic winding being provided for maintaining the contacts openwhile said resistance in the work circuit is maintained at the said lowvalue; and the counteracting electromagnetic winding for destroying theeiiect of the secondary electromagnetic winding and permitting thecontacts to close when the resistance in the work circuit is againrestored to its minimum allowable value.

5. A protective circuit interrupting device `:for ciicuits includingwork devices, comprising in combination, an electromagnet of thesolenoid type including a core having a plunger armature; a pair ofnormally-closed contacts adapted to be opened by said armature; a pairof auxiliary contacts noi'- mally open, one of said contacts beingoperatively connected to one of the normallyclosed contacts; a mainwinding oii/the core, 011e end of which yis connected to one ofthenormally-closed contacts; a secondary winding of comparatively higherresistance than the main winding, connected in shunt with the.normally-closed contacts; and a third lwinding of lesser resistancethan the secondary winding and connected in series therewith but woundin opposition to the aforementioned two windings, one end of saidwinding being connected to one of the normally-open contacts.

6. A protective circuit interrupting device for circuits including workdevices, comprising in combination, an armature; a pair ofnormally-closed contacts; a main winding for operating the armature toopen said contacts when the resistance in thework circuit is reducedbelow 'a minimum allowable value; a secondary winding of comparativelyhigher resistance than the main winding,

.wound in the same direction as said main winding and connected inparallel therewith, said secondary winding being adapted to maint-ainthe armature in its attracted, contact opening position while theresistance in the work circuit is maintained at' its aforementionedlois7 value; and a counteracting :winding of lesser resistance than thesec- /ondary winding and connected in series with the secondary winding,but wound in opposition thereto, 'said counteracting winding beingineiective to counteract the secondary winding while the resistance inthe work circuit is maintained below its minimum allowable value.

7. A protective circuit interrupting device for circuits including workdevices, comprising in combination, an armature; a pair ofnormally-closed contacts; a lnain winding for operating the armature too en said contacts when the resistance in t e work circuit is reducedbelow a minimum allowable value; a secondary windin of comparative- 1yhigher resistance than the main winding, wound in the same direction assaid main winding and connected in parallel therewith,

vsaid secondary winding being adaptedto maintain the armature 1n itsattracted contact-opening position while the resistance in the workcircuit is maintained at its aforementioned low value; and acounteracting winding of lesser resistance than the secondary windingand connected in series but wound in opposition to' said secondarywinding, said counteracting winding becoming effective to destroy theeffect of the second-4 ary winding when the resistance in the workcircuit is substantially equal to the resis'tance of said counteractingwinding. i

8. A protective circuit lnterrupting device for circuits including workdevices, comprising in combination, an armature; a pair ofnormally-closed contacts; a main winding for operating the armature toopen said contacts when the resistance in the work circuit is reducedbelow a minimum allowable value; a secondary winding of comparativelyhigher resistance than the main winding, wound in the same direction assaid main winding and connected in parallel therewith, said secondarywinding being adapted to maintain the armature in its attractedcontact-opening position while the resistance in the work circuit ismaintained at its aforementioned low value; and acounteracting windingof lesser resistance than the secondary winding and connected in seriesbut wound in opposition to said secondary winding, said counteractingwinding being ineffective to counteract the secondary winding whiletheresistance in the work circuit is of .comparatively lesser value thanthe resistance in the counteracting winding.

9. A protective circuit interrupting device for circuits including workdevices, comprising in combination, an electromagnet of the solenoidtype including a core having a plunger armature; a pair of main contacts1nclud1ng a stationary contact, and a movable,contact supported by aspring arm and normally in engagement with the stationary contact, saidmovable contact being adapted to be moved out of engagement with thestationary contact by the plunger armature; a main winding on the magnetcore, one end fof said winding being connected to the main stationarycontact; an auxiliary pair of contacts includinga stationary member, anda movable contact member carried by the spring arm' of the main contactsso that said auxiliary contacts will be open when the main contacts areclosed; a secondary winding on the core, of higher resistance than themain winding, and connected in shunt with the main contacts, saidsecondary winding being adapted to maintain the armature in attracted,main-contact-opening position after a current tlow in excess of themaximum allowable value has passed through lthe main winding andenergized the core to attract the armature, said excessive current fiowbeing due to the resistance in the work circuit falling below itsminimum allowable value; and a counteracting winding wound on the corereversely to said other two windings and brought into series connectionwith the secondary winding by the closing of the auxiliary contacts,said winding being eective to counteract the secondary winding andrelease the armature to permit the main. contacts to close onlyy whenresistance in the work circuit substantially equals-the resistance ofthe counteracting winding.

"In testimony whereof I hereto aix my signature.

JOHN T. FITZSIMMNS.

CII

